In my opinion they work and woek well!!I had often wondered why people did not use protien skimmers in thier freshwater tamks i am by no means a salt water expert in fact i have never even had a salt water set up but i have always been facinated with filtration and always check it out what ever setup is being looked at by me .I have been experimenting with this on my live feed tank 180 gal in my garage .For filtration i have An OSI with 1600 gph two 20 gallon containers one is a sump one just a tote with lucky bamboo.With a filter sock 30 micron tons of course sponge and only 5 gollons of mediabio balls that i had on hand.Plus the protien skimmer rated for a 65 gallon salt set up and one koralia 4 power head for water movement .any way in my pics i tested the water as i was feeding and you can see it is slightly elevated during feeding of coarse but at all times i have between 3 and 400 fish in this tank and it's always in check with a once a week water change ..granted it's massive about 80 % but i have been impressed ....to say the least ..I plan on doing this to a larger scale with my 675 gal tank..... Enough of me talking i am posting a coule pics and lets get some good discusion going on this subject ..a couple pics showing salinity witch i do use salt in all my tanks something i personly believe in also the tank and the fitration and of coarse the skimmer i believe the proof is in the poison you can clearly see it seperates the organic matter from the fresh water tank 



I get what is in the container every 24 hours














I get what is in the container every 24 hours









